Problem: William eats at a restaurant and the cost of his meal is $\$31.00$. He would like to leave a $10\%$ tip. What is his total bill including tip?
Answer: The tip amount is equal to $10\% \times \$31.00$ To calculate a $10\%$ tip, move the decimal point in $\$31.00$ one place to the left. $10\%$ $\times \$31.00$ $\$3.10$ The cost of the meal plus the amount of the tip will equal the total bill amount. $\$31.00 + \$3.10 = $ $\$34.10$ The total cost of the bill is $\$34.10$.